The ratio of the length of rode to the water depth is known as the scope.
Anchoring with sufficient scope brings the direction of strain close to parallel with the seabed. In general the longer your rode the better. 10:1 scope is preferable in windy conditions.
An average cruising boat is recommended to carry at least 300 feet of rode, which will allow for 10:1 scope in 25 feet of water (5 feet allotted for free-board height). This will ensure that most of the time you can anchor with 10:1 Scope.
It is generally accepted that in a storm situation we strive to put out 10:1 scope, but why? See how anchors maximum holding power varies with changing scope.
Many cruisers find that 10:1 scope is a nice compromise between rode length and maximizing anchors holding power.
|Scope||% Max Hold Power||Deg|